Machine Tool Position Measurement Thermal Displacement Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current position measurement methods in machine tools, such as those using touch trigger probes and laser sensors, face challenges in accurately measuring the length of position measurement sensors like touch trigger probes, especially when they change due to thermal displacement, and require expensive CCD cameras or manual intervention, leading to inefficiencies and increased costs.
Innovation Solution
A position measurement method and system that includes a tool sensor, a reference block, and a position measurement sensor, which acquires and calculates a length compensation value by measuring the relative position between the tool sensor and the reference block, allowing for accurate measurement of objects even if the sensor length changes, without the need for CCD cameras or manual handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a touch trigger probe is used to measure object position, then measurement capability is provided, but the sensor length changes due to thermal displacement causing measurement inaccuracy
Solution Approach 1:
The system continuously monitors the actual length of the touch trigger probe using a laser sensor and feeds this information back to the control device. The control device calculates the difference between the actual length and reference length, then applies compensation to the measured object position to eliminate thermal displacement errors.
Solution Approach 2:
The system dynamically adjusts the measurement parameters by incorporating the actual sensor length (which changes with temperature) into the calculation. The control device uses the measured actual length parameter to compensate the object position measurement, transforming the unstable sensor length into a compensatable variable.
2Measurement precision
If a CCD camera is used to measure sensor length, then measurement accuracy is improved, but system cost and complexity increase
Solution Approach 1:
The patent replaces the optical measurement system (CCD camera) with a laser-based measurement system. The laser sensor measures the sensor length by detecting light blockage, which is then processed electronically. This substitution maintains measurement accuracy while significantly reducing system complexity and cost.
Solution Approach 2:
The system uses a relatively simple and inexpensive laser sensor instead of an expensive CCD camera system. The laser sensor provides sufficient measurement capability for the application while being more cost-effective and easier to integrate into the existing machine tool control system.
3Ease of manufacture
If manual intervention is used to measure sensor length, then equipment cost is reduced, but productivity and measurement efficiency decrease
Solution Approach 1:
The system performs self-measurement of the sensor length using the laser sensor and automated control device. The touch trigger probe system automatically measures its own length changes without requiring external manual intervention or separate measurement equipment, maintaining low cost while achieving high productivity.
Solution Approach 2:
The laser sensor continuously monitors the sensor length throughout the measurement process, and the control device continuously calculates and applies compensation. This continuous automated measurement and compensation process eliminates manual intervention while maintaining high measurement efficiency and productivity.
4Device complexity
If the sensor length is not compensated, then system simplicity is maintained, but measurement accuracy deteriorates due to thermal displacement
Solution Approach 1:
The system separates the measurement function into two independent parts: the laser sensor measures the sensor length, and the control device calculates and applies compensation to the object position measurement. This segmentation allows the compensation function to be added without fundamentally changing the existing simple measurement system structure.
Solution Approach 2:
The control device acts as an intermediary that receives data from both the laser sensor (actual sensor length) and the touch trigger probe (object position measurement), processes this information, and outputs the compensated measurement. This intermediary approach integrates compensation into the existing system without requiring major structural changes.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enables high-accuracy, cost-effective measurement of object positions in machine tools by eliminating the need for expensive equipment and manual intervention, ensuring precise compensation for sensor length changes due to thermal displacement or other causes.
Implementation Method 1
When the laser light 14 is obstructed by a substance and therefore a light-receiving rate becomes a certain rate or less, the laser sensor 10 generates a signal
Implementation Method 2
the touch sensor 20 and the touch trigger probe 30 have respective different operating resistances
Data Source
AI summary
A position measurement method to measure a position of an object in a machine tool includes a tool sensor position acquisition stage, a reference block position acquisition stage, a relative position calculation stage, a reference tool position acquisition stage, a position measurement sensor measurement stage, a length compensation value calculation stage, and a position measurement stage. In the position measurement stage, the measurement position of the object is compensated using a length direction compensation value of a position measurement sensor calculated in the length compensation value calculation stage. The object is measured by the position measurement sensor installed to a main spindle.